Fmuser Fu-15b 0w-15w Premium Professional Pc Control Fm Transmitter with Gp100 Antenna and Power Supply and Audio Cable transmit power continuously adjustable from 0W to 15W constant power, the whole band has 3 ~ 5W margin with PC control port, through computer manipulation of the machine with temperature protection, when the transmitter when the temperature is too high, automatically protected Operating voltage 12V ~ 16V (rated voltage 15V)